JPG decompressed and compressed again, will it affect colors and color space?
The color space is the same: sRGB, so expect no transformation there, but know that Jpeg is a compressed format, a lossy compression format designed to make file sizes small at the expense of quality. A terrible format if you are applying transformations.

Every time you decompress an image, change the geometry or color, and re-compress the image again you will get new compression artifacts. Do an image search for "macroblocking" and "compression artifacts" to understand the horrors of the JPEG format.